1. Field of the Invention
The present invention relates to a device for epicardial support and/or the assuming of cardiac activity having a double membrane consisting of an elastic inner membrane and a non-expandable outer membrane as well as a closed cavity formed therebetween which can be inflated and deflated by means of a fluid.
2. Description of Related Art
Such a device—although one which works pericardially—is known for example from the document DE 199 51 220 A1. The device is a minimally-invasive, i.e. percutaneously implantable system for the mechanical support and temporary substitution of the heart's pumping function. After probing the pericardial sac, the device is inserted into the pericardial sac percutaneously in collapsed state or surgically positioned in the pericardial sac at the end of an operation with the double membrane surrounding the right and left ventricles. Thereby the device in its deflated state is so thin that a compression of the adjacent organs will be avoided. Subsequent implantation, the cavity of the double membrane is rhythmically supplied through a connecting tube with a fluid which can either be a gas (helium or CO2) or a suitable liquid. Due to this rhythmic inflation and deflation of the double membrane's cavity and because the outer membrane is not expandable in contrast to the inner membrane, the double membrane surrounding the heart effects pressure transmission and compression of the heart. In so doing, blood is urged from the right ventricle into the pulmonary artery and simultaneously from the left ventricle into the aorta or, with available pumping function of the heart, aids in the systolic ejection of the cardiac muscle.
For patients who undergo heart surgery at the present time, however, a temporary pace-maker probe is still being attached epicardially at the end of the operation. In the case of asystolia (electrical cardiac standstill) or bradycardia (too slow of a heart rate) during the critical post-operative phase, the two temporary probes can stimulate the heart by means of an externally attached pacemaker. The probe cables are extracted after five to seven days, which is possible without reopening the chest. Yet regarded as a disadvantage is that those temporary pacemaker probe must every time be sewn on.
Should ventricular arrhythmias occur during the post-operative phase (ventricular tachycardia or ventricular fibrillation), a defibrillator must be used to restore the heart's normal rhythm. An external defibrillator attachable to the body is hereby used, although it is known on the one hand that only 10-20% of the energy in the form of electric work generated by the defibrillator (200 to 360 joules) acts directly on the heart, while most is absorbed by the surrounding tissue. On the other hand, implantable defibrillators can be used, whereby the probes positioned in the ventricle are usually left inside the patient for many years. Yet also known in this case is that usually only 30-50% of the energy generated by an implanted defibrillator (16 to 34 joules) has any effect on the heart.